This invention relates to a manufacturing process and a manufacturing apparatus of a molded skin material used for an interior decoration member for a vehicle such as a motorcar or the like.
Molded skin materials used for an automobile or other vehicle interior decoration member such as an instrument panel, a door panel and so on, generally have a complicated curved surface. Additionally, such materials can have any desired pattern thereon such as seams, specific formed wrinkles or the like. A conventional manufacturing process comprises charging a plastic sol into a mold having a predetermined curved shape and/or a pattern. An alternative previous method is known as slush molding. Plastic powder is coated on a predetermined shaped molding mold surface by electrodeposition coating and the coating is then fused by heating so that a film thereof is formed thereon. The former process is defective in that air is liable to be confined to the contact surface between the charged liquid and the mold, thereby producing bubbles or voids and pinholes are liable to be created in the molded film due to the air included in the liquid. The latter process is defective in that, because the powder is coated on the surface after it is charged with electricity, the flowing rate and the flowing amount of the powder from a gun are limited, resulting in lowering the coating efficiency. This is especially so when a comparatively large-sized and complicated molded product is to be manufactured. The problem is that it is difficult to coat on every sideward and rearward part of the curved mold surface. Therefore, it is inevitable for this process to provide a multiple head type gun apparatus wherein a large number of guns are disposed at various necessary angles in relation to the molded surface.